Patent literature 1: JP H11-308107 A (corresponding to U.S. Pat. No. 6,687,555 B1)
In an inductive load such as an electromagnetic valve (also referred to as a solenoid valve), an electromagnetic actuator, a linear solenoid is used as power source. An electronic control apparatus controls an actuation (a drive) of the inductive load. The electronic control apparatus controls current supplied to the linear solenoid, and thus controls the actuation of the inductive load. This kind of an electronic control apparatus includes apparatus described in Patent literature 1.
The electronic control apparatus described in Patent literature 1 includes a FET (a field effect transistor), an A/D converter (an analog-digital converter), and a control CPU. The FET is placed between the inductive load and a power source. The A/D converter converts a current detection signal of a linear solenoid into a digital signal from an analog signal. The control CPU detects a current value flowing through the linear solenoid based on the current detecting signal converted into the digital signal. The control CPU performs a feedback control of a supply current of the linear solenoid, so that an average value of the detected current value is equal to a target current value. Specifically, the control CPU sets a duty ratio based on a deflection between the average value of the detected current value and the target current value, and generates a PWM (pulse-width modulation) signal according to the duty ratio. The control CPU causes the FET to turn on and off according to the PWM signal, and performs a PWM control of the supply current of the linear solenoid. The control CPU controls the actuation of the inductive load through such a current feedback control.
The inventors of the present application have found the following. In order to improve accuracy of the drive control of the inductive load in the electronic control apparatus of Patent literature 1, the average value of the detection current value may be detected precisely. In order to detect the average value of the detection current value with a sufficient precision, it may be considered that the sampling number of the detection current value is increased, for example. When the sampling numbers of the detection current value is increased, processing load of the control CPU may increase. The sampling number of the detection current value represents the number of times of sampling of the detection current value. Especially in a control CPU without a hardware IP, all the arithmetic concerning the detection current value may have to in a software manner. An effect to the processing load on the control CPU may increase.